The Red Ledge occurrence is located at an elevation of approximately 2000 metres on the west side of a small valley between Toby and Stark creeks.
Regionally, the area is underlain by Proterozoic clastic sedimentary rocks of the Purcell and Windermere supergroups and by Cretaceous intrusive rocks (Geoscience Map 1995-1). The Purcell Supergroup strata include the Aldridge, Creston, Kitchener, Dutch Creek and Mount Nelson formations. The Windermere Supergroup overlies the Purcell Supergroup rocks and includes the Toby Formation and Horsethief Creek Group (Paper 1990-1).
Locally, rocks of the Kitchener and Dutch Creek formations have been further subdivided and assigned to the Van Creek and Gateway formations (Open File 1990-26). The Van Creek Formation consists mainly of coarse- to medium-grained, light-grey to dark-green quartzite, siltstone and silty argillite. The beds have consistent thickness of between 20 and 50 centimetres with slightly undulose bases and truncated tops. The Van Creek Formation grades upwards into thinly bedded quartzite of the Gateway Formation. The Gateway Formation is subdivided into the Hg1 and Hg2 members. The Hg1 member consists of an interbedded sequence of quartzite, green siltstone and buff dolomitic siltstone and dolomite. Bed thicknesses vary from generally 2 to 10 centimetres in the fine-grained quartzite to 10 to 50 centimetres in the upper dolomite. The contact with the underlying Van Creek Formation is gradational or marked by the basaltic flows of the Nicol Creek Formation. The Hg2 member consists of a 90-metre thick, cream to buff-weathering dolomite unit. The dolomite displays stromatolitic laminations, cream-coloured chert intercalations and rare salt casts. Bed thickness varies from 50 centimetres to 2 metres. The sedimentary rocks have undergone regional metamorphism to at least greenschist facies.
In the area the rocks are complexly folded and are transected by many faults. The regional structure consists of relatively open folds plunging gently to the northwest, which together form a broad anticline extending across most of the Purcell Mountains. Southwest-dipping thrust faults and north–to-northwest–trending normal faults are common.
The Red Ledge occurrence consists of seven small veins and fractures containing galena, tetrahedrite, sphalerite, chalcopyrite and pyrite within the Hg1 member of the Lower Gateway Formation. Siderite and limonite are also reported. The most important sulphide occurrence is in dolomite and has been exposed by trenching. Here, massive galena and tetrahedrite are found within an irregular, steep, northerly plunging, pipe-like body with an average diameter of 0.5 metre. The mineralized zone is exposed in outcrop over an area of 7.5 by 24 metres.
In 1968, samples are reported to have assayed 0.10 per cent lead and 0.31 per cent zinc over 6 metres of mineralized dolomite adjacent to the Red Ledge fault (Property File - Cominco Ltd. [1968-08-14]: Property Examination Report - Red Ledge Claims).
In 1980, a chip sample across 1 metre of the mineralized pipe assayed 706 grams per tonne silver, 27.2 per cent lead, 1.89 per cent zinc and 0.22 per cent copper (Assessment Report 8639).
The area has been explored since the 1800s in conjunction with the nearby Mineral King (MINFILE 082KSE001) past-producing mine. In 1968, Cominco examined the area as the Red Ledge claims. In 1980 and 1981, Echo Mines completed programs of geochemical sampling, geological mapping and ground electromagnetic surveys on the area.
